The present invention is generally related to saboted projectiles and more particularly to armor piercing fin stabilized discarding sabot (APFSDS) tank ammunition.
The present known gun systems have reached their peaks as far as pressure limitations, so further minor improvement to the weapon system is not generally believed to be practical. A major change such as a new high pressure gun system is generally thought to be needed to achieve the muzzle velocities required to defeat the newer armor targets. These types of drastic changes, of course, are expensive and time consuming to develop.
It is also generally believed that the present state of the art for direct tank fired ammunition is reaching a point of diminishing returns. It appears that without a major breakthrough in sabot fired rounds the "state of the art" armor target will become superior to the penetrator performance, rendering all present rounds obsolete.
Because of gun design limitations that now exist, design consideration is now being directed toward drastic changes to the parasitic hardware (the sabot) by using newer, higher strength materials, and sabot configurations that provide higher strength sabot structures which will permit the reduction in weight of the parasitic hardware.
In conventional sabot designs, it is known that there are areas of the sabot structure that will permit the reduction in material weight without jeopardizing the sabot integrity. In addition, the forward bell (or front bourrelet), used as a support for the forward end of the flight projectile (penetrator) during acceleration in the gun and as an aerodynamic lifting surface during the discard process can, especially in the case of high L/D (20 or more) projectile designs, contribute too much lift on forward end of the sabot segment. In this case the sabot segment interferes with the flight projectile at the aft end inducing high initial yaw contributing to inaccuracy.
One proposed solution to this type of problem was recently disclosed in U.S. Pat. No. 4,920,889. In this case, a groove or a series of holes are provided at the base of the forward bell so that it will separate from its segment upon emergence of the projectile from the gun muzzle. This early separation of the bell portion is designed to minimize the effect of the sabot segment rotation on the penetrator as the segment rotates out and away from the penetrator body upon launch. However, separation is not parallel to the path of the projectile and therefore rotation still has an undesirable effect on projectile accuracy.
Another approach is disclosed in U.S. Pat. No. 4,608,927. In this design the front bourrelet is replaced with three bore riding ribs which prevent balloting in the bore of the gun and allow passage of air into an annular scoop or pocket formed in the forward perimeter of the rear bourrelet so as to catch passing air that is void of turbulence and thus minimize oscillations during flight of the projectile.
A still further approach to mass reduction in a sabot assembly is disclosed in U.S. Pat. No. 4,326,464. In this patent a plurality of longitudinal gussets are used to reduce the overall weight and mass of the sabot while retaining the necessary strength to withstand acceleration forces during launch and provide the desired separation without adversely affecting penetrator flight.
U.S. Pat. No. 4,284,008 teaches placement of the obturator at about the center of gravity of the subcaliber penetrator and distributing the forces of launch using a double tapered or ramp configuration fore and aft of the obturating band to enhance inbore stability.
U.S. Pat. No. 4,524,695 teaches the use of a plurality of equally spaced bore riding fins aft of the obturator and adjacent the fins on the penetrator projectile. These bore riding fins assist in stabilizing the projectile during launch through the gun bore to minimize inbore instability.